221011-33-2Relevant articles and documents
Preparation and intramolecular cyclization of bis(carbodiimides). Synthesis and X-ray structure of 1,3-diazetidine-2,4-diimine derivatives
Alajarin,Molina,Sanchez-Andrada,Foces-Foces
, p. 1121 - 1130 (2007/10/03)
Aza-Wittig reactions of bis(iminophosphorane) 1 derived from 2,2'- diazidobiphenyl with aromatic isocyanates provided dibenzo[d,f]-1,3- diazetidino[1,2-a]diazepine derivatives 2 in moderate yields. Similar results can be achieved from the reaction of 2,2-bis(isothiocyanato)biphenyl 4 with aryliminophosphoranes. Treatment of bis(isothiocyanate) 4 with arylamines and further dehydrosulfurization of the resulting bis(thioureas) leads to the seven-membered ring guanidines 8. N-2(2'-Azido)biphenyl-N'-arylcarbodiimides 13 react with 1 equiv of triphenylphosphane to give zwitterionic compounds 15, which undergo either hydrolytic cleavage to afford the guanidines 8 or react with 1 equiv of aromatic isocyanates to provide 2. Cross-experiments suggest that the conversion 15 ← 2 takes place through a nonisolable bis(carbodiimide) that undergoes an intramolecular [2 + 2] cycloaddition at the final step. The reaction of bis(iminophosphorane) 1 with an excess of carbon dioxide leads to a mixture of the tricyclic 1,3-diazetidine derivative 6 and the 14-membered cyclic bis(carbodiimide) 23, which decomposes by thermal treatment. Compound 6 can also be obtained along with the seven- membered cyclic urea derivatives 24 from the reaction of bis(iminophosphorane) 1 with the carbon dioxide source Boc2O/DMAP system. A comprehensive mechanistic scheme for the aza-Wittig reactions studied is conveniently presented. The molecular and crystal structures of 1-(4- methoxyphenyl)-2-(4-methoxyphenyl)iminodibenzo[d,f]-1,3-diazetidino[1,2- a]diazepine (2c) and [a,c]bis[dibenzo[d,f][1,3]diazepino]-1,3-diazetidine (6) have been determined by X-ray analysis.
